1. Field of the Invention
The present invention relates to a color image reader, and in particular, to a color scanner or a color facsimile.
2. Description of the Related Art
Conventional light sources for scanners include hot cathode fluorescent lamps each having a filament section at both ends. An advantage of hot cathode fluorescent lamps is their large luminous energy but they are disadvantageous in that they have a large lamp diameter of 100 mmf and a short life of about 5, 000 H. Japanese Patent Application Laying Open (KOKAI) No. 2-57392 discloses a lighting circuit for hot cathode fluorescent lamps.
Japanese Patent Application Laying Open (KOKAI) No. 3-34712 discloses a color image reader that allows three light sources to flash sequentially at a high speed and which uses a CCD.
By using three circuits as shown in Japanese Patent Application Laying Open (KOKAI) No. 2-57392, three hot cathode fluorescent lamps can be allowed to light easily.
Small cold cathode fluorescent lamps having diameter of 4 or 3 mint with no filament section at either end have recently been implemented. The sensitivity of CCDs has also recently been improved to enable much faster reading.
Although cold cathode fluorescent lamps are smaller than hot cathode fluorescent lamps and have a longer life (about 10, 000 H), they disadvantageously have a smaller luminous energy and requires a high voltage of 1, 200 VAC compared to 300 VAC in h hot cathode fluorescent lamps.
Thus, the use of a cold cathode fluorescent lamp enables a small scanner to be implemented but results in a lower reading speed.